| 摘要 |
A pH controller for a liquid stream includes a pump (22) to inject a pH-changing additive into the stream, a mixing chamber (38), an electrode (18) to measure the pH of the emerging liquid, and means to adjust operation of the pump in accordance with that measurement. The mixing chamber (38) is of annular form, defined between two concentric cylinders (30, 34) the inner one (34) of which is rotated. The rotation speed and the throughput can be adjusted to give very thorough mixing and hence to enable the pH to be held at a steady value. The flow regime appears to involve Taylor vortices (40) which together define a single helical path for the liquid. The liquid treated may comprise effluent form nuclear fuel reprocessing (e.g. containing nitric acid and ferric nitrate) to which is added NaOH solution to achieve a pH of 9-10.5, to precipitate ferric hydroxide floc. <IMAGE> |
